Clean Transport 101: Repower

In previous posts we've seen that our priorities should be to Reduce, then Replace, then Repower; and we've gone through some guidelines for how to do the first two. So how should we Repower? 

Electrify Everything is the best rule of thumb here. Remember that Reducing and Replacing are a higher priority than Repowering, so I'm not saying "Just electrify the status quo" - but when it comes to the question of how we Repower our vehicles, whatever types of vehicles they may be, "electrify it!" should be our first thought. Then, if it turns out electrifying it isn't practical in the short term, we start searching for alternative methods like hydrogen or biofuels. 

Hydrogen seems like it will have some useful applications in the decarbonisation process. But it also has a ton of difficulties that will need to be overcome, so it shouldn't be the first solution we reach for - it should be the backup we turn to when electrification won't work. 

One inherent difficulty with hydrogen is inefficiency. Hydrogen gas isn't found in substantial quantities anywhere we could realistically harvest it; Earth's hydrogen atoms are mostly locked up in compounds like water, so we need to separate it out from the other components - eg using electricity to electrolyse water. Then, to actually use the hydrogen to power a car/train/whatever, we'd need to compress it (so it fits in the tank of the vehicle) then use a hydrogen fuel cell to generate electricity, which is used to run the motors. This conversion of energy from electricity to hydrogen and back again is really inefficient - almost two thirds of the energy is lost in this process, leaving you with only 37% to actually drive the vehicle with. (1) 

Using hydrogen to power cars is very inefficient (my graphs, from data in The Big Switch)

So why is this hugely inefficient process even on the table? 

Battery electric vehicles don't have these issues with efficiency losses, but their big disadvantage at the moment is a combination of relatively low range, and relatively slow "refilling". In a petrol or diesel vehicle, you can generally go a long way on a single tank, and when the tank gets empty it's a quick process to refill it - so you're back on the road again quickly. But with batteries, even "fast chargers" will take 30-60 minutes, while conventional powerpoints can take many hours. 

When it comes to private cars, this isn't a big deal - most private cars drive very short distances, and sit idle most of the time. We drive them a bit before work, they sit idle for eight hours or so, we drive them a bit after work, and they sit idle overnight - minimal time in use and plenty of time for charging, even on conventional powerpoints. Even if you road trip on your holidays, having a meal or toilet break while the car recharges generally makes good sense - it won't cause too many headaches. It's certainly not going to "end the weekend". 

Hydrogen makes more sense for intensively-used commercial vehicles (via NDLA)

But commercial vehicles often have much more intensive usage patterns - on the road all day, with minimal downtime for charging. Hydrogen vehicles can have longer range, and can be refilled roughly as quickly as petrol or diesel, so there's much less downtime - which means more time on the road, doing the job, earning money. 

In an intensively-used commercial vehicle, these are advantages worth paying for - and worth copping those energy inefficiencies for. But for a private car that could easily charge while you're at work or asleep? Not so much. 

Of course, as battery and charging technology improves, ranges will get longer and charging will get faster, so hydrogen's advantage will gradually erode. So when it comes to private and commercial light vehicles, hydrogen might have a role to play as a transition fuel, but it's probably never going to play a big role. 

Electric vehicle and charger (via Walter Baxter)

So batteries win the car market - but what policies should we use to transition our fleet? 

The trick is to encourage Repowering without discouraging Reducing and Replacing. So introducing increasingly-strict fuel efficiency standards (2) is probably the highest priority - it very efficiently favours EVs over ICEVs without distorting their relationship to public and active transport, which is exactly what we want. It also helps address one of the key barriers to uptake - model availability. When car companies are forced to lower average emissions across their Australian sales, they will be compelled to include the EV models they currently sell overseas. 

Accelerating the rollout of charging infrastructure, particularly in regional areas where private investment mightn't go (and where cycling and PT may be less viable) is another good move - as is setting standards to ensure home charging is widely accessible (2).

Direct subsidies (rebates, waivers on taxes and fees, etc) can conflict with the Reduce and Replace goals, so we should be very wary. At the very least, we have to make sure any subsidies are focused on the initial purchase price and not on ongoing costs - particularly since it's the initial purchase price, not the ongoing costs, that deters people from buying EVs. Ideally, direct purchase subsidies should also be as mode-agnostic as possible - for example, including e-bikes and annual PT tickets in the subsidy, as well as electric cars (3). 

Lastly, the "perks" like free parking or EV-only lanes encourage people to drive. In Norway, there's evidence these perks led the car's mode share to rise from 65% to 83%, mostly at the expense of public transport (but also a bit from active transport); they don't just displace ICE car trips, they displace trips on more sustainable modes. This conflicts with Reducing and Replacing, so these perks should be avoided. 

Battery electric buses seem to be winning the fight (via Ryanmirjanic)

When it comes to buses, again batteries have a big lead. Examples from Sydney to Shenzhen make it clear that batteries can handle typical duty cycles of city buses. For long-distance coaches (eg V/Line, Greyhound) it's less clear - prototype coaches have done huge distances on batteries, but as far as I'm aware, none in revenue service, so hydrogen might still have a chance there. The remit of the Victorian government's zero-emissions bus trial includes coaches, so it'll be interesting to see the results there. 

Overhead Line Electrification will be key to decarbonising railways (via Backbone Campaign)

On the railways, there's a third option - overhead line electrification, which effectively means the train is constantly plugged directly into the grid (4). I've now done a more detailed post on Repowering our railways, but the short version is: all the other options require you to carry the fuel on the train (whether it's a battery, hydrogen gas, diesel, or coal) while OLE allows the train to just grab whatever energy it needs as it moves along, meaning it has access to functionally infinite fuel without having to carry any of it. There are of course costs involved with building the infrastructure, but in terms of fundamental efficiency, there is no gas or battery chemistry that can ever compete with that. So OLE is the winner for the mainlines, wherever trains are reasonably frequent and/or fast; on quiet branch lines, it's a toss-up between batteries and hydrogen depending on the speed of the train and the length of the line. 

The electric Eviation Alice at Paris Air Show in 2019 (via Matti Blume)

Aviation is still an unanswered question. Very small battery planes already exist, and they're on the cusp of commercial viability for a few niche applications. But the leap from these small planes to full-sized jet liners is huge, and batteries have a long way to go before they're up to the task - so it's certainly possible hydrogen will beat them to the punch. However, the IPCC seems to think biofuels might win the aviation game in the short term. Like hydrogen, biofuels have big problems compared to electricity, so they should only be used when absolutely necessary - but it seems like aviation might be the one sector where those tradeoffs are worth it. We'll see. 

A Shell hydrogen pump (via GPA)

When we think about the role hydrogen will play, it's important to keep the politics in mind as well. Right now, ~95% of hydrogen is made through a process called Steam Methane Reforming (SMR), which takes natural gas and blasts it with steam to form hydrogen gas and methane. This actually emits more carbon than just burning the fossil fuels directly, and it currently accounts for 830 mT of CO2 annually - equivalent to the UK's and Indonesia's emissions combined - so producing substantially more hydrogen this way would be a climate disaster. 

Hydrogen can be made in a clean, green way - electrolysing water using electricity from renewable sources is completely zero carbon. But currently most of it isn't made this way, since it's more expensive. 

But the big fossil fuel companies are very keen for hydrogen to be the main replacement for petrol and diesel, because they see it as a way to use up what would otherwise be stranded assets - they have the rights to huge natural gas fields, which they'll never be able to sell if the world stops burning gas directly. But their stock price depends on those assets having value - so they're trying to find a new market for it, and they're counting on the public either not knowing the difference between dirty hydrogen and green hydrogen, or buying the argument that dirty hydrogen is a "transition fuel" on the way to green hydrogen. 

Scott Morrison and Boris Johnson at COP26 (via Number 10)

So the big fossil fuel companies are pushing hydrogen hard - they're very keen to undersell the role electrification will play in the future, and oversell the role hydrogen will play, in the hope that it'll benefit their bottom line. And it seems pretty clear that this is why Scott Morrison, and a bunch of other politicians who have otherwise shown no interest in reducing emissions, are so keen on hydrogen. (5)

Hydrogen probably will play a role in decarbonising transport, and the economy more broadly - but there are a lot of vested interests keen to overstate the role it will play, so we need to be approaching these problems with that "Electrify everything" mindset first. And hydrogen absolutely can be clean - but there are a lot of vested interests who will try to blur the line between dirty and green hydrogen, so we need to be vigilant in making sure that when production capacity ramps up, it's the clean green electrolysis that gets the investment. 

So that brings us to the end of this series of posts. I've published an addendum fleshing out the Repowering of our railways in more detail, but overall I'm really keen to hear people's feedback on the series. I want to polish this and make it as robust as I can, so poke holes in it, make suggestions to strengthen it, whatever you've got - I want to hear it! 

1. I just included the example of electrolysis and fuel cells here for simplicity, but there are a couple of other ways you can do this which change the numbers slightly, like creating the hydrogen from SMR rather than electrolysis, and burning the hydrogen rather than using a fuel cell. But they all come to basically the same conclusion - around 2/3 lost, 1/3 left to do stuff with. Advancements in technology might improve these efficiencies a bit at the margins, but there's not much scope to fundamentally change this dynamic. 

2. I really like the Grattan Institute's policies on tightening emissions standards and on improving access to charging outlined in this document - I think they're the right policies and I think Grattan make the case well for them. But just to add some context, there are other policies in this document I don't agree with, some of which I've dealt with above. FWIW I believe Grattan is advocating for import and luxury taxes to be scrapped for EVs because they have a long-standing belief those taxes should be abolished altogether, not because of anything to do with transport emissions. 

3. The Victorian Greens have proposed this, and I strongly support it, but again to add some context, I don't support the Free PT policy they launched at the same time - "What's deterring people isn't the price, it's that the system currently doesn't meet their needs"

4. OLE is actually possible for the buses, too - trolleybuses are a well-understood technology for intra-city buses, they still exist in some places around the world and may stack up better than batteries in some places in Australia. However, most of the places best suited to trolleybuses (ie routes that are or should be frequent enough to warrant investing in the poles and wires) are also the kinds of places a tram makes most sense. So while I'd definitely be pleased to see governments investing in trolleybuses, I think in most cases we're more likely to expand the tram network we're familiar with than bring in these new unfamiliar buses. 

5. To be fair, some politicians and activists who genuinely are keen on reducing emissions are also keen on hydrogen, so this isn't to suggest all hydrogen-boosters are fossil fuel cronies - just that we should treat these apparent changes of heart with the skepticism they deserve.